Methods, systems and apparatus to trigger a workflow in a cloud computing environment

ABSTRACT

Methods, apparatus and articles of manufacture to provide workflow subscription management in a cloud computing environment are disclosed. Example methods disclosed herein include causing display of a template corresponding to an event topic that is to trigger a workflow associated with a first workflow subscription, the first workflow subscription included in a plurality of workflow subscriptions having a hierarchy, the template to include a first field to specify whether at least one other workflow subscription associated with the event topic is to be blocked until a hierarchically dominant workflow subscription has at least one of been notified of the event topic or taken action based on the event topic. Disclosed example methods also include triggering the workflow in response to an event notification associated with the event topic.

RELATED APPLICATION(S)

This patent arises from a continuation of U.S. patent application Ser.No. 15/371,407 (now U.S. Pat. No. 10,552,180), which is entitled“METHODS, SYSTEMS AND APPARATUS TO TRIGGER A WORKFLOW IN A CLOUDCOMPUTING ENVIRONMENT,” and which was filed on Dec. 7, 2016. Priority toU.S. patent application Ser. No. 15/371,407 is hereby expressly claimed.U.S. patent application Ser. No. 15/371,407 is hereby incorporated byreference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to cloud computing and, moreparticularly, to triggering workflow(s) in a cloud computingenvironment.

BACKGROUND

Virtualizing computer systems provides benefits such as an ability toexecute multiple computer systems on a single hardware computer,replicating computer systems, moving computer systems among multiplehardware computers, and so forth.

“Infrastructure-as-a-Service” (also commonly referred to as “IaaS”)generally describes a suite of technologies provided by a serviceprovider as an integrated solution to allow for elastic creation of avirtualized, networked, and pooled computing platform (sometimesreferred to as a “cloud computing platform”). Enterprises may use IaaSas a business-internal organizational cloud computing platform(sometimes referred to as a “private cloud”) that gives an applicationdeveloper access to infrastructure resources, such as virtualizedservers, storage, and networking resources. By providing ready access tothe hardware resources required to run an application, the cloudcomputing platform enables developers to build, deploy, and manage thelifecycle of a web application (or any other type of networkedapplication) at a greater scale and at a faster pace than ever before.

Cloud computing environments may include many processing units (e.g.,servers). Other components of a cloud computing environment includestorage devices, networking devices (e.g., switches), etc. Current cloudcomputing environment configuration relies on much manual user input andconfiguration to install, configure, and deploy the components of thecloud computing environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an example system constructed in accordance with theteachings of this disclosure for managing a cloud computing platform.

FIG. 2 illustrates an example generation of a multi-machine blueprint bythe example blueprint manager of FIG. 1.

FIG. 3 illustrates an example installation of deployed virtual machinesand associated servers acting as hosts for deployment of componentservers for a customer.

FIG. 4 illustrates an example implementation of a virtual appliancecapable of providing workflow subscription management in accordance withthe teachings of this disclosure.

FIG. 5A is a block diagram of an example implementation of thesubscription manager and an example workflow subscription graphical userinterface of the virtual appliance illustrated in FIG. 4.

FIG. 5B is a block diagram illustrating an example exchange ofinformation between the example subscription manager of FIG. 5A, anexample event broker of FIG. 4, and an example orchestrator also shownin FIG. 4.

FIG. 5C is a block diagram illustrating an example exchange ofinformation between the example subscription manager of FIG. 5A, theexample event broker of FIG. 4, and the example orchestrator also shownin FIG. 4.

FIG. 6 is a flowchart representative of example computer readableinstructions that may be executed to implement the example workflowsubscription graphical user interface and the example subscriptionmanager of the example virtual appliance of FIG. 4.

FIG. 7 is a flowchart representative of example computer readableinstructions that may be executed to implement the example subscriptionmanager of the example virtual appliance of FIG. 4.

FIG. 8 is a block diagram of an example processing platform structuredto execute the example computer readable instructions of FIGS. 6 and/or7 and to implement the example virtual appliance of FIG. 4.

The figures are not to scale. Wherever possible, the same referencenumbers will be used throughout the drawing(s) and accompanying writtendescription to refer to the same or like parts, elements, etc.

DETAILED DESCRIPTION

Cloud computing is based on the deployment of many physical resourcesacross a network, virtualizing the physical resources into virtualresources, and provisioning the virtual resources to perform cloudcomputing services and applications. Example systems for virtualizingcomputer systems are described in U.S. patent application Ser. No.11/903,374, entitled “METHOD AND SYSTEM FOR MANAGING VIRTUAL AND REALMACHINES,” filed Sep. 21, 2007, and granted as U.S. Pat. No. 8,171,485,U.S. Provisional Patent Application No. 60/919,965, entitled “METHOD ANDSYSTEM FOR MANAGING VIRTUAL AND REAL MACHINES,” filed Mar. 26, 2007, andU.S. Provisional Patent Application No. 61/736,422, entitled “METHODSAND APPARATUS FOR VIRTUALIZED COMPUTING,” filed Dec. 12, 2012, all threeof which are hereby incorporated herein by reference in their respectiveentireties.

Cloud computing platforms may provide many powerful capabilities forperforming computing operations. However, taking advantage of thesecomputing capabilities manually may be complex and/or requiresignificant training and/or expertise. Prior techniques to provide cloudcomputing platforms and services often require customers to understanddetails and configurations of hardware and software resources toestablish and configure the cloud computing platform. Methods andapparatus disclosed herein facilitate the management of virtual machineresources in cloud computing platforms.

A virtual machine is a software computer that, like a physical computer,runs an operating system and applications. An operating system installedon a virtual machine is referred to as a guest operating system. Becauseeach virtual machine is an isolated computing environment, virtualmachines (VMs) can be used as desktop or workstation environments, astesting environments, to consolidate server applications, etc. Virtualmachines can run on hosts or clusters. The same host can run a pluralityof VMs, for example.

Example methods and apparatus disclosed herein provide for automation ofmanagement tasks, such as provisioning multiple virtual machines for amultiple-machine computing system (e.g., a group of servers thatinter-operate), linking provisioned virtual machines and tasks todesired systems to execute those virtual machines or tasks, reclaimingcloud computing resources that are no longer in use, and/or workflowsubscription management, etc. The improvements to cloud managementsystems (e.g., the vCloud Automation Center (vCAC) from VMware®, thevRealize Cloud Automation Software from VMware®), interfaces, portals,etc. disclosed herein may be utilized individually and/or in anycombination. For example, all or a subset of the described improvementsmay be utilized.

As used herein, availability refers to the level of redundancy requiredto provide continuous operation expected for the workload domain. Asused herein, performance refers to the computer processing unit (CPU)operating speeds (e.g., CPU gigahertz (GHz)), memory (e.g., gigabytes(GB) of random access memory (RAM)), mass storage (e.g., GB hard drivedisk (HDD), GB solid state drive (SSD)), and power capabilities of aworkload domain. As used herein, capacity refers to the aggregate numberof resources (e.g., aggregate storage, aggregate CPU, etc.) across allservers associated with a cluster and/or a workload domain. In examplesdisclosed herein, the number of resources (e.g., capacity) for aworkload domain is determined based on the redundancy, the CPU operatingspeed, the memory, the storage, the security, and/or the powerrequirements selected by a user. For example, more resources arerequired for a workload domain as the user-selected requirementsincrease (e.g., higher redundancy, CPU speed, memory, storage, security,and/or power options require more resources than lower redundancy, CPUspeed, memory, storage, security, and/or power options).

Example Virtualization Environments

Many different types of virtualization environments exist. Three exampletypes of virtualization environment are: full virtualization,paravirtualization, and operating system virtualization.

Full virtualization, as used herein, is a virtualization environment inwhich hardware resources are managed by a hypervisor to provide virtualhardware resources to a virtual machine. In a full virtualizationenvironment, the virtual machines do not have direct access to theunderlying hardware resources. In a typical full virtualizationenvironment, a host operating system with embedded hypervisor (e.g.,VMware ESXi®) is installed on the server hardware. Virtual machinesincluding virtual hardware resources are then deployed on thehypervisor. A guest operating system is installed in the virtualmachine. The hypervisor manages the association between the hardwareresources of the server hardware and the virtual resources allocated tothe virtual machines (e.g., associating physical random access memory(RAM) with virtual RAM). Typically, in full virtualization, the virtualmachine and the guest operating system have no visibility and/or directaccess to the hardware resources of the underlying server. Additionally,in full virtualization, a full guest operating system is typicallyinstalled in the virtual machine while a host operating system isinstalled on the server hardware. Example full virtualizationenvironments include VMware ESX®, Microsoft Hyper-V®, and Kernel BasedVirtual Machine (KVM).

Paravirtualization, as used herein, is a virtualization environment inwhich hardware resources are managed by a hypervisor to provide virtualhardware resources to a virtual machine and guest operating systems arealso allowed direct access to some or all of the underlying hardwareresources of the server (e.g., without accessing an intermediate virtualhardware resource). In a typical paravirtualization system, a hostoperating system (e.g., a Linux-based operating system) is installed onthe server hardware. A hypervisor (e.g., the Xen® hypervisor) executeson the host operating system. Virtual machines including virtualhardware resources are then deployed on the hypervisor. The hypervisormanages the association between the hardware resources of the serverhardware and the virtual resources allocated to the virtual machines(e.g., associating physical random access memory (RAM) with virtualRAM). In paravirtualization, the guest operating system installed in thevirtual machine is configured also to have direct access to some or allof the hardware resources of the server. For example, the guestoperating system may be precompiled with special drivers that allow theguest operating system to access the hardware resources without passingthrough a virtual hardware layer. For example, a guest operating systemmay be precompiled with drivers that allow the guest operating system toaccess a sound card installed in the server hardware. Directly accessingthe hardware (e.g., without accessing the virtual hardware resources ofthe virtual machine) may be more efficient, may allow for performance ofoperations that are not supported by the virtual machine and/or thehypervisor, etc.

Operating system virtualization is also referred to herein as containervirtualization. As used herein, operating system virtualization refersto a system in which processes are isolated in an operating system. In atypical operating system virtualization system, a host operating systemis installed on the server hardware. Alternatively, the host operatingsystem may be installed in a virtual machine of a full virtualizationenvironment or a paravirtualization environment. The host operatingsystem of an operating system virtualization system is configured (e.g.,utilizing a customized kernel) to provide isolation and resourcemanagement for processes that execute within the host operating system(e.g., applications that execute on the host operating system). Theisolation of the processes is known as a container. Several containersmay share a host operating system. Thus, a process executing within acontainer is isolated the process from other processes executing on thehost operating system. Thus, operating system virtualization providesisolation and resource management capabilities without the resourceoverhead utilized by a full virtualization environment or aparavirtualization environment. Alternatively, the host operating systemmay be installed in a virtual machine of a full virtualizationenvironment or a paravirtualization environment. Example operatingsystem virtualization environments include Linux Containers LXC and LXD,Docker™, OpenVZ™, etc.

In some instances, a data center (or pool of linked data centers) mayinclude multiple different virtualization environments. For example, adata center may include hardware resources that are managed by a fullvirtualization environment, a paravirtualization environment, and anoperating system virtualization environment. In such a data center, aworkload may be deployed to any of the virtualization environments.

Workflow Management

Prior workflow management systems executed in cloud environments areusually limited to executing a defined set of workflows related toperforming a variety of tasks such as provisioning virtual machines.However, customers of cloud computing platforms and services may want toextend the workflows performed in the cloud environment and/or havegreater control over how and when such workflows are performed. However,extending workflows and/or controlling how/when such workflows areexecuted in existing cloud computing platforms is typically performedmanually by a system administrator having specialized knowledge of theoperations of such workflows. In order to amend the operations of theworkflows (e.g., customize the workflow), the system administrator mustrevise the code representing the workflow and/or identify workflow stubsat which additional workflow tasks can be attached to an existingworkflow. Further, in order to remove such additional workflow tasks ata later time, the system administrator must review the workflow code andremove all additional tasks added thereto. Often, a tenant administratorlacks the specialized knowledge and/or the confidence to make suchchanges. In view of the above-mentioned limitations of prior workflowmanagement systems, such prior systems tend to be difficult to reviseand, therefore, inflexible.

Unlike such prior systems, example cloud management systems (e.g., suchas the vRealize Automation Cloud Automation Software from VMware®)having the workflow management system disclosed herein provide thetenant administrator with the ability to trigger the operation of acustom or non-custom workflow based on a system generated event andfurther based on a user-specified condition. Further, the tenantadministrator can easily prevent the workflow from triggering at anytime by selecting an inactivation feature available on a display. Agraphical user interface disclosed herein supplies a display by which atenant administrator can select (or specify) a workflow, select asystem-generated event and specify a condition related to the event tothereby form a workflow subscription. Based on the event and thespecified condition, the selected/specified workflow is triggered.

Disclosed herein is an example virtual appliance in a cloud computingenvironment that includes a graphical user interface that responds to auser-selected event topic by causing a corresponding event schema to bedisplayed, and that also includes a subscription manager to trigger aworkflow based on an event notification corresponding to the event topicand based on a condition corresponding to the event schema beingsatisfied. In some disclosed examples, the event schema includes schemafields and the graphical user interface responds to selection of a firstone of the schema fields by generating an input field by which a usercan enter a threshold value. In further disclosed examples, thegraphical user interface supplies the threshold value to thesubscription manager and the subscription manager determines whether thecondition has been satisfied based on the threshold value. In yetfurther examples, the subscription manager includes a comparator thatcompares the threshold value to a payload value collected from an eventpayload included in the event notification and the payload value isassociated with the field of interest. In still further examples, thesubscription manager determines, based on the comparison, whether thepayload value bears a specific relationship to the threshold value. Insome examples, the graphical user interface generates a displayincluding a list of workflows, and a list of event topics and thegraphical user interface collects a workflow identifier corresponding toa user-selected one of the workflows and collects an event topicidentifier corresponding to the user-selected event topic. Thesubscription manager subscribes to an event broker to receive the eventnotification corresponding to the event topic.

Example methods for triggering a workflow are disclosed herein. Someexample methods include, causing, by executing an instruction with atleast one processor, an event schema to be displayed in response to afirst input identifying an event topic that corresponds to the eventschema. Disclosed example methods further include accessing a secondinput identifying a field included in the event topic schema and a thirdinput identifying a threshold value corresponding to the field and, inresponse to an event notification corresponding to the event topic andbased on the threshold value having a defined relationship to a payloadvalue included in an event payload contained in the event notification,triggering a workflow, by executing an instruction with at least oneprocessor. Example methods also include examining the event payload toidentify the field and to identify the payload value contained in thefield, and, evaluating an actual relationship between the payload valueand the threshold value, to determine if the actual relationshipsatisfies the defined relationship. Further example methods includeregistering to receive the event notification when an event related tothe event topic occurs. In some example methods, the event topicincludes provisioning a virtual machine. Still further disclosed examplemethods include accepting a fourth input identifying the definedrelationship. In still further example methods, the defined relationshipis at least one of: 1) the payload value being equal to the thresholdvalue, 2) the payload value being greater than the threshold value, and3) the payload value being less than the threshold value. Still furtherexample methods include assigning a subscription identifier to at leastone of the event topic, the field and the threshold value, and storingthe subscription identifier, the event topic, the field and thethreshold value as a workflow subscription. Yet other example methodsinclude in response to an activation input, activating the workflowsubscription, wherein activating the workflow subscription causes anevent broker to send the event notification corresponding to the eventtopic to a subscription manager when an event corresponding to the eventtopic occurs. The subscription manager performs the triggering of theworkflow, in response to the event notification corresponding to theevent topic and based on the threshold value having a definedrelationship to a payload value included in the event payload containedin the event notification.

Also disclosed herein are example instructions to cause a processor tocause a corresponding event schema to be displayed in response to afirst input identifying an event topic, to access a second inputidentifying a field included in the event topic schema and a third inputidentifying a threshold value corresponding to the field, and, based onreceiving an event notification corresponding to the event topic andbased on the threshold value having a defined relationship to a payloadvalue included in an event payload contained in the event notification,to trigger a workflow. Further example instructions cause the processorto identify the field in the event payload and identify the payloadvalue contained in the field, and, evaluate an actual relationshipbetween the payload value and the threshold value, to determine if theactual relationship satisfies the defined relationship. Exampledisclosed instructions further cause the processor to register toreceive the event notification when an event (generated by a service)related to the event topic occurs. In some examples, the event topicincludes provisioning a virtual machine. Further disclosed instructionscause the processor to accept a fourth input identifying the definedrelationship. The defined relationship can be at least one of: 1) thepayload value being equal to the threshold value, 2) the payload valuebeing greater than the threshold value, and 3) the payload value beingless than the threshold value.

These and other example methods, apparatus, systems and articles ofmanufacture (e.g., physical storage media) to implement a workflowtriggering subscription in a cloud computing environment are disclosedin further detail below

Illustrated Examples

FIG. 1 depicts an example system 100 constructed in accordance with theteachings of this disclosure for managing a cloud computing platform.The example system 100 includes an application director 106 and a cloudmanager 138 to manage a cloud computing platform provider 110 asdescribed in more detail below. As described herein, the example system100 facilitates management of the cloud provider 110 and does notinclude the cloud provider 110. Alternatively, the system 100 could beincluded in the cloud provider 110.

The cloud computing platform provider 110 provisions virtual computingresources (e.g., virtual machines, or “VMs,” 114) that may be accessedby users of the cloud computing platform 110 (e.g., users associatedwith an administrator 116 and/or a developer 118) and/or other programs,software, device. etc.

An example application 102 of FIG. 1 includes multiple VMs 114. Theexample VMs 114 of FIG. 1 provide different functions within theapplication 102 (e.g., services, portions of the application 102, etc.).One or more of the VMs 114 of the illustrated example are customized byan administrator 116 and/or a developer 118 of the application 102relative to a stock or out-of-the-box (e.g., commonly availablepurchased copy) version of the services and/or application components.Additionally, the services executing on the example VMs 114 may havedependencies on other ones of the VMs 114.

As illustrated in FIG. 1, the example cloud computing platform provider110 may provide multiple deployment environments 112, for example, fordevelopment, testing, staging, and/or production of applications. Theadministrator 116, the developer 118, other programs, and/or otherdevices may access services from the cloud computing platform provider110, for example, via REST (Representational State Transfer) APIs(Application Programming Interface) and/or via any other client-servercommunication protocol. Example implementations of a REST API for cloudcomputing services include a vCloud Administrator Center™ (vCAC) and/orvRealize Automation™ (vRA) API and a vCloud Director™ API available fromVMware, Inc. The example cloud computing platform provider 110provisions virtual computing resources (e.g., the VMs 114) to providethe deployment environments 112 in which the administrator 116 and/orthe developer 118 can deploy multi-tier application(s). One particularexample implementation of a deployment environment that may be used toimplement the deployment environments 112 of FIG. 1 is vCloud DataCentercloud computing services available from VMware, Inc.

In some examples disclosed herein, a lighter-weight virtualization isemployed by using containers in place of the VMs 114 in the developmentenvironment 112. Example containers 114 a are software constructs thatrun on top of a host operating system without the need for a hypervisoror a separate guest operating system. Unlike virtual machines, thecontainers 114 a do not instantiate their own operating systems. Likevirtual machines, the containers 114 a are logically separate from oneanother. Numerous containers can run on a single computer, processorsystem and/or in the same development environment 112. Also like virtualmachines, the containers 114 a can execute instances of applications orprograms (e.g., an example application 102 a) separate fromapplication/program instances executed by the other containers in thesame development environment 112.

The example application director 106 of FIG. 1, which may be running inone or more VMs, orchestrates deployment of multi-tier applications ontoone of the example deployment environments 112. As illustrated in FIG.1, the example application director 106 includes a topology generator120, a deployment plan generator 122, and a deployment director 124.

The example topology generator 120 generates a basic blueprint 126 thatspecifies a logical topology of an application to be deployed. Theexample basic blueprint 126 generally captures the structure of anapplication as a collection of application components executing onvirtual computing resources. For example, the basic blueprint 126generated by the example topology generator 120 for an online storeapplication may specify a web application (e.g., in the form of a Javaweb application archive or “WAR” file including dynamic web pages,static web pages, Java servlets, Java classes, and/or other property,configuration and/or resources files that make up a Java webapplication) executing on an application server (e.g., Apache Tomcatapplication server) that uses a database (e.g., MongoDB) as a datastore. As used herein, the term “application” generally refers to alogical deployment unit, including one or more application packages andtheir dependent middleware and/or operating systems. Applications may bedistributed across multiple VMs. Thus, in the example described above,the term “application” refers to the entire online store application,including application server and database components, rather than justthe web application itself. In some instances, the application mayinclude the underlying hardware and/or virtual computing hardwareutilized to implement the components.

The example basic blueprint 126 of FIG. 1 may be assembled from items(e.g., templates) from a catalog 130, which is a listing of availablevirtual computing resources (e.g., VMs, networking, storage, etc.) thatmay be provisioned from the cloud computing platform provider 110 andavailable application components (e.g., software services, scripts, codecomponents, application-specific packages) that may be installed on theprovisioned virtual computing resources. The example catalog 130 may bepre-populated and/or customized by an administrator 116 (e.g., IT(Information Technology) or system administrator) that enters inspecifications, configurations, properties, and/or other details aboutitems in the catalog 130. Based on the application, the exampleblueprints 126 may define one or more dependencies between applicationcomponents to indicate an installation order of the applicationcomponents during deployment. For example, since a load balancer usuallycannot be configured until a web application is up and running, thedeveloper 118 may specify a dependency from an Apache service to anapplication code package.

The example deployment plan generator 122 of the example applicationdirector 106 of FIG. 1 generates a deployment plan 128 based on thebasic blueprint 126 that includes deployment settings for the basicblueprint 126 (e.g., virtual computing resources' cluster size, CPU,memory, networks, etc.) and an execution plan of tasks having aspecified order in which virtual computing resources are provisioned andapplication components are installed, configured, and started. Theexample deployment plan 128 of FIG. 1 provides an IT administrator witha process-oriented view of the basic blueprint 126 that indicatesdiscrete actions to be performed to deploy the application. Differentdeployment plans 128 may be generated from a single basic blueprint 126to test prototypes (e.g., new application versions), to scale up and/orscale down deployments, and/or to deploy the application to differentdeployment environments 112 (e.g., testing, staging, production). Thedeployment plan 128 is separated and distributed as local deploymentplans having a series of tasks to be executed by the VMs 114 provisionedfrom the deployment environment 112. Each VM 114 coordinates executionof each task with a centralized deployment module (e.g., the deploymentdirector 124) to ensure that tasks are executed in an order thatcomplies with dependencies specified in the application blueprint 126.

The example deployment director 124 of FIG. 1 executes the deploymentplan 128 by communicating with the cloud computing platform provider 110via a cloud interface 132 to provision and configure the VMs 114 in thedeployment environment 112. The example cloud interface 132 of FIG. 1provides a communication abstraction layer by which the applicationdirector 106 may communicate with a heterogeneous mixture of cloudprovider 110 and deployment environments 112. The deployment director124 provides each VM 114 with a series of tasks specific to thereceiving VM 114 (herein referred to as a “local deployment plan”).Tasks are executed by the VMs 114 to install, configure, and/or startone or more application components. For example, a task may be a scriptthat, when executed by a VM 114, causes the VM 114 to retrieve andinstall particular software packages from a central package repository134. The example deployment director 124 coordinates with the VMs 114 toexecute the tasks in an order that observes installation dependenciesbetween VMs 114 according to the deployment plan 128. After theapplication has been deployed, the application director 106 may beutilized to monitor and/or modify (e.g., scale) the deployment.

The example cloud manager 138 of FIG. 1 interacts with the components ofthe system 100 (e.g., the application director 106 and the cloudprovider 110) to facilitate the management of the resources of the cloudprovider 110. The example cloud manager 138 includes a blueprint manager140 to facilitate the creation and management of multi-machineblueprints and a resource manager 144 to reclaim unused cloud resources.The cloud manager 138 may additionally include other components formanaging a cloud environment.

The example blueprint manager 140 of the illustrated example manages thecreation of multi-machine blueprints that define the attributes ofmultiple virtual machines as a single group that can be provisioned,deployed, managed, etc. as a single unit. For example, a multi-machineblueprint may include definitions for multiple basic blueprints thatmake up a service (e.g., an e-commerce provider that includes webservers, application servers, and database servers). A basic blueprintis a definition of policies (e.g., hardware policies, security policies,network policies, etc.) for a single machine (e.g., a single virtualmachine such as a web server virtual machine and/or container).Accordingly, the blueprint manager 140 facilitates more efficientmanagement of multiple virtual machines and/or containers than manuallymanaging (e.g., deploying) basic blueprints individually. Examplemanagement of multi-machine blueprints is described in further detail inconjunction with FIG. 2.

The example blueprint manager 140 of FIG. 1 additionally annotates basicblueprints and/or multi-machine blueprints to control how workflowsassociated with the basic blueprints and/or multi-machine blueprints areexecuted. As used herein, a workflow is a series of actions anddecisions to be executed in a virtual computing platform. The examplesystem 100 includes first and second distributed execution manager(s)(DEM(s)) 146A and 146B to execute workflows. According to theillustrated example, the first DEM 146A includes a first set ofcharacteristics and is physically located at a first location 148A. Thesecond DEM 146B includes a second set of characteristics and isphysically located at a second location 148B. The location andcharacteristics of a DEM may make that DEM more suitable for performingcertain workflows. For example, a DEM may include hardware particularlysuited for performance of certain tasks (e.g., high-end calculations),may be located in a desired area (e.g., for compliance with local lawsthat require certain operations to be physically performed within acountry's boundaries), may specify a location or distance to other DEMSfor selecting a nearby DEM (e.g., for reducing data transmissionlatency), etc. Thus, the example blueprint manager 140 annotates basicblueprints and/or multi-machine blueprints with capabilities that can beperformed by a DEM that is labeled with the same or similarcapabilities.

The resource manager 144 of the illustrated example facilitates recoveryof cloud computing resources of the cloud provider 110 that are nolonger being activity utilized. Automated reclamation may includeidentification, verification and/or reclamation of unused,underutilized, etc. resources to improve the efficiency of the runningcloud infrastructure.

FIG. 2 illustrates an example implementation of the blueprint 126 as amulti-machine blueprint generated by the example blueprint manager 140of FIG. 1. In the illustrated example of FIG. 2, three example basicblueprints (a web server blueprint 202, an application server blueprint204, and a database (DB) server blueprint 206) have been created (e.g.,by the topology generator 120). For example, the web server blueprint202, the application server blueprint 204, and the database serverblueprint 206 may define the components of an e-commerce online store.

The example blueprint manager 140 provides a user interface for a userof the blueprint manager 140 (e.g., the administrator 116, the developer118, etc.) to specify blueprints (e.g., basic blueprints and/ormulti-machine blueprints) to be assigned to an instance of amulti-machine blueprint 208. For example, the user interface may includea list of previously generated basic blueprints (e.g., the web serverblueprint 202, the application server blueprint 204, the database serverblueprint 206, etc.) to allow selection of desired blueprints. Theblueprint manager 140 combines the selected blueprints into thedefinition of the multi-machine blueprint 208 and stores informationabout the blueprints in a multi-machine blueprint record defining themulti-machine blueprint 208. The blueprint manager 140 may additionallyinclude a user interface to specify other characteristics correspondingto the multi-machine blueprint 208. For example, a creator of themulti-machine blueprint 208 may specify a minimum number and a maximumnumber of each blueprint component of the multi-machine blueprint 208that may be provisioned during provisioning of the multi-machineblueprint 208.

Accordingly, any number of virtual machines (e.g., the virtual machinesassociated with the blueprints in the multi-machine blueprint 208)and/or containers may be managed collectively. For example, the multiplevirtual machines corresponding to the multi-machine blueprint 208 may beprovisioned based on an instruction to provision the multi-machineblueprint 208, may be power cycled by an instruction, may be shut downby an instruction, may be booted by an instruction, etc. As illustratedin FIG. 2, an instruction to provision the multi-machine blueprint 208may result in the provisioning of a multi-machine service formed fromone or more VMs 114 that includes virtualized web server(s) 210A,virtualized application server(s) 210B, and virtualized databaseserver(s) 210C. The number of virtual machines and/or containersprovisioned for each blueprint may be specified during the provisioningof the multi-machine blueprint 208 (e.g., subject to the limitsspecified during creation or management of the multi-machine blueprint208).

The multi-machine blueprint 208 maintains the reference to the basicblueprints 202, 204, 206. Accordingly, changes made to the blueprints(e.g., by a manager of the blueprints different than the manager of themulti-machine blueprint 208) may be incorporated into futureprovisioning of the multi-machine blueprint 208. Accordingly, anadministrator maintaining the source blueprints (e.g., an administratorcharged with managing the web server blueprint 202) may change or updatethe source blueprint and the changes may be automatically propagated tothe machines provisioned from the multi-machine blueprint 208. Forexample, if an operating system update is applied to a disk imagereferenced by the web server blueprint 202 (e.g., a disk image embodyingthe primary disk of the web server blueprint 202), the updated diskimage is utilized when deploying the multi-machine blueprint.Additionally, the blueprints may specify that the machines 210A, 210B,210C of the multi-machine service 210 provisioned from the multi-machineblueprint 208 operate in different environments. For example, somecomponents may be physical machines, some may be on-premises virtualmachines, and some may be virtual machines at a cloud service.

Several multi-machine blueprints may be generated to provide one or morevaried or customized services. For example, if virtual machines deployedin the various States of the United States require different settings, amulti-machine blueprint could be generated for each state. Themulti-machine blueprints could reference the same build profile and/ordisk image, but may include different settings specific to each state.For example, the deployment workflow may include an operation to set alocality setting of an operating system to identify a particular statein which a resource is physically located. Thus, a single disk image maybe utilized for multiple multi-machine blueprints reducing the amount ofstorage space for storing disk images compared with storing a disk imagefor each customized setting.

FIG. 3 illustrates an example installation of deployed appliances orvirtual appliances (vAs) (e.g., VMs 114 and/or containers 114 a) andassociated virtualized servers acting as hosts for deployment ofcomponent servers (e.g., Web server, application server, databaseserver, etc.) for a customer. The vAs can be deployed as an automationtool, for example, used to deliver VMs and associated applications foron-premises automation and/or handling of external cloud resources(e.g., Microsoft Azure™, Amazon Web Services™, etc.).

As shown in the example of FIG. 3, an installation 300 includes a loadbalancer (LB) 310 to assign tasks and/or manage access among a pluralityof vAs 320, 322, 324. Each vA 320-324 is a deployed VM 114 and/orcontainer 114 a. In this example, the vA 320 communicates with aplurality of component or host servers 330, 332, 334, 336 which storecomponents for execution by users (e.g., Web server 210A with Webcomponents, App server 210B with application components, DB server 210Cwith database components, etc.). As shown in the example of FIG. 3,component servers 334, 336 can stem from component server 330 ratherthan (or in addition to) directly from the virtual appliance 320,although the vA 320 can still communicate with such servers 334, 336.The LB 310 enables the multiple vAs 320-324 and multiple servers 330-336to appear as one device to a user. Access to functionality can then bedistributed among appliances 320-324 by the LB 310 and among servers330-336 by the respective appliance 320, for example. The LB 310 can useleast response time, round-robin, and/or other method to balance trafficto vAs 320-324 and servers 330-336, for example.

In the example installation 300, each vA 320, 322, 324 includes amanagement endpoint 340, 342, 344. Each component server 330, 332, 334,336 includes a management agent 350, 352, 354, 356. The managementagents 350-356 can communicate with their respective endpoint 340 tofacilitate transfer of data, execution of tasks, etc., for example.

In certain examples, the management agents 350-356 synchronize componentservers 330-336 with the vA 320-234 and facilitate host access andassociated services (e.g., hostd, ntpd, sfcbd, slpd, wsman, vobd, etc.).The management agents 350-356 can communicate with their respectiveendpoint 340 to facilitate transfer of data, execution of tasks, etc.,for example. The relationship between management endpoint 340, 342, 344and associated management agents 350, 352, 354, 356 can be used todeploy and install software on multiple component machines 330, 332,334, 336.

In certain examples, a graphical user interface associated with a frontend of the load balancer 310 guides a customer through one or morequestions to determine system requirements for the installation 300.Once the customer has completed the questionnaire and provided firewallaccess to install the agents 350-356, the agents 350-356 communicatewith the endpoint 340 without customer involvement. Thus, for example,if a new employee needs a Microsoft Windows® machine, a manager selectsan option (e.g., clicks a button, etc.) via the graphical user interfaceto install a VM 114 and/or container 114 a that is managed through theinstallation 300. To the user, he or she is working on a single machine,but behind the scenes, the virtual appliance (vA) 320 is accessingdifferent servers 330-336 depending upon what functionality is to beexecuted.

In certain examples, agents 350-356 are deployed in a same data centeras the endpoint 340 to which the agents 350-356 are associated. Thedeployment can include a plurality of agent servers 330-336 distributedworldwide, and the deployment can be scalable to accommodate additionalserver(s) with agent(s) to increase throughput and concurrency, forexample.

FIG. 4 illustrates an example implementation of the vA 320. In theexample of FIG. 4, the vA 320 includes an example service provisioner410, an example orchestrator 420, an example event broker 430, anexample authentication provider 440, an example internal reverse proxy450, an example data storage 460, an example catalog 465, an exampleworkflow subscription graphical user interface (GUI) 470, an examplesubscription manager 480, and example services 490. The components 410,420, 430, 440, 450, 460, 470, 480, 490 of the vA 320 may be implementedby one or more of the VMs 114. The example service provisioner 410provides services to provision interfaces (e.g., Web interface,application interface, etc.) for the vA 320. The example orchestrator(e.g., vCO) 420 is an embedded or internal orchestrator that canleverage a provisioning manager, such as the application director 106and/or cloud manager 138, to provision VM services but is embedded inthe vA 320. For example, the orchestrator 420 can be used to invoke ablueprint to provision a manager for services. In some examples, theorchestrator 420 includes a library of workflows that can be selectedfor execution.

Example services 490 can include catalog services, identity services,component registry services, approval services, resource managementservices, event broker services, IaaS, XaaS (“Anything-as-a-Service”),etc. Catalog services provide a user interface via which a user canrequest provisioning of different preset environments (e.g., a VMincluding an operating system and software and some customization,etc.), for example. Identity services facilitate authentication andauthorization of users and assigned roles, for example. The componentregistry maintains information corresponding to installed and deployedservices (e.g., uniform resource locators for services installed in aVM/vA, etc.), for example. The approval services provide a method bywhich a request to provision a virtual machine (or service) can beapproved by a system administrator(s). The resource management servicescan control the leasing, expiration and reclamation of managedresources. The event broker 430 provides a messaging broker forevent-based communication, for example. The IaaS provisions one or moreVMs and/or containers for a customer via the vA 320. The XaaS can extendthe provisioning to also request, approve, provision, operate, anddecommission any type of catalog items (e.g., storage, applications,accounts, and anything else that the catalog provides as a service).

The example event broker 430 provides a mechanism to handle tasks whichare transferred between the services 190 and the orchestrator 420. Theexample authentication provider 440 (e.g., VMware Horizon™ services,etc.) authenticates access to services and data, for example.

The components of the vA 320 access each other through REST API callsbehind the internal reverse proxy 450 (e.g., a high availability (HA)proxy HAProxy) which provides a high availability load balancer andproxy for Transmission Control Protocol (TCP)- and Hypertext TransferProtocol (HTTP)-based application requests. In this example, the proxy450 forwards communication traffic from within the vA 320 and/or betweenvAs 320, 322, 324 of FIG. 3 to the appropriate component(s) of the vA320. In certain examples, services access the local host/proxy 450 on aparticular port, and the call is masked by the proxy 450 and forwardedto the particular component of the vA 320. Since the call is masked bythe proxy 450, components can be adjusted within the vA 320 withoutimpacting outside users.

The example vA 320 of FIG. 4 further includes the example workflowsubscription GUI 470, that, in combination with the example services490, the example event broker 430, the example subscription manager 480,and the example orchestrator 420, implement an example workflowsubscription service to enable the extensibility of provisioningworkflows in accordance with the teachings of this disclosure. In otherwords, the workflow subscription service enables the provisioningworkflows to be easily extended to include additional tasks. The exampleworkflow subscription service implemented by the vA 320 enables acustomer, such as the tenant administrator 116, or any other authorizeduser, to control when provisioning workflows (or workflow related toprovisioning activities) are performed based on events reported by anyof the services 490 to the event broker 430. In some examples, asdisclosed further herein, the workflow subscription service furtherallows the tenant administrator to control when workflows are performedbased on events coupled with user-specified conditions.

An example implementation of the workflow subscription GUI 470 and theexample subscription manager 480 is shown in FIG. 5A. In the illustratedexample of FIG. 5A, the example workflow subscription GUI 470 includesan example template generator 502 to generate a displayableuser-viewable template implemented, for example, in a webpage format (orany other desired format) that allows the tenant administrator to createa “workflow subscription.” In some examples, the tenant administratorcreates the workflow subscription by entering information into thetemplate and/or selecting information presented by the template. Theworkflow subscription is created by, for example, specifying a workflowto be performed, an event that is to be used, in part, to trigger theoperation of the workflow, and one or more conditions to be evaluatedagainst a desired value before the workflow begins operating. Thetemplate generator 502 supplies the template to any screen, display ormonitor such as the monitor associated with the tenant administratorwork station 116 for presentation thereat. In some examples, the tenantadministrator begins by selecting a check box or a radial button (or anyother selectable icon) on the template to indicate that a workflowsubscription is to be created. In some examples, in response toreceiving the subscription selection from the tenant administrator workstation 116, the template generator 502 causes the template to display alist of selectable workflows. In some such examples, the workflowsubscription GUI 470 can obtain the list of selectable workflows fromthe example data storage 460, from the example orchestrator 420, (orfrom any storage device) via, an example workflow subscription GUIcommunicator 506. The workflow subscription GUI communicator 506 can becommunicably coupled to, for example, the data storage 460, the eventbroker 430, the example subscription manager 480, the orchestrator 420,etc. In some examples, in lieu of providing a list of selectableworkflows, the template generated by the template generator 502 providesa text box (or any other input field) into which the tenantadministrator can enter an executable script that, when executed,performs a workflow.

In some examples, the template generator 502 includes a list ofuser-selectable event topics in the template. A selected event topic maybe used to trigger the operation of the workflow entered or selected bythe tenant administrator. In some examples, the user-selectable eventtopics are associated with (and/or) generated by one or more of theexample services 490 and are reported by one or more of the services 490to the example event broker 430. As used herein, an event topicdescribes a set of events having a same logical intent and a samestructure. Every event is an instance of an event topic. Further anevent topic is a type of event message that is sent to the event broker430 by one or more of the services 490. An event can indicate a changein the state of one of the services 490 that produces the event (or anyof the entities managed by any such one of the services 490). An eventis an informational element (or data structure) in which informationabout an event occurrence is recorded. An event notification or messagetransports information about the event between the various services 490and the event broker 430 and between the event broker 430 and thesubscription manager 480. In some examples, the list of user-selectableevent topics is stored in the data storage 460 and accessed by theworkflow subscription GUI 470 using the workflow subscription GUIcommunicator 506 for display via the template.

In some examples, the user-selectable event topics include a postapproval event topic, a pre-approval event topic, an event log defaultevent topic, a blueprint configuration event topic, a resourcereclamation event topic, a business group configuration event topic, anorchestration server configuration event topic, a machine lifecycleevent topic, a machine provisioning event topic, etc. The post approvaland pre-approval event topics are associated with the approval serviceand can be used to trigger workflows associated with obtainingenterprise approvals for an operation. (For example, if a user wouldlike to provision a new virtual machine, the pre-approval event topicmay be used to generate a workflow that will require a set ofadministrative approvals be obtained before the virtual machine isprovisioned.) The event log default event topic represents the additionof an entry in an event log and can be generated by an event logservice. The event log can be a recordation of any of a set ofoccurrences/operations performed by any of the components of the vA 320.The blueprint configuration event topic can be associated with thecreation, deletion or updating of a blueprint configuration and can begenerated by a composition service. The resource reclamation completionevent can represent a resource lease expiring and reclamation of theresource subject to the expired lease. The resource reclamationcompletion event can be generated by a resource management service. Thebusiness group configuration event topic can represent a business groupbeing created, updated or deleted and can be generated by an identityservice. The orchestration server configuration (XaaS) event topic canrepresent an orchestrator server configuration being created, updated,deleted or modified and can be generated by an advanced-designerservice. The machine lifecycle event topic can represent an IaaS actionbeing run on a provisioned machine and can be generated by an IaaSservice. The machine provisioning event topic can represent an IaaSmachine in the process of being provisioned and can be generated by anIaaS service.

In some examples, the user-selectable event topics displayed via thetemplate includes an event topic identifier, an event name, an eventdescription, a service name that identifies the service associated withgenerating and/or producing the event, a blockable field indicatingwhether the event topic is blockable such that one or more othersubscriptions will (or will not) be blocked from event notificationuntil a hierarchically dominant subscription has been notified and/ortaken action based on the event topic, a replyable field indicatingwhether the event topic is replyable such that the workflow subscriptioncan generate a reply notification to be sent to the service thatgenerated the event when the workflow finishes, and an event schema thatdescribes the structure of the event's payload.

In addition, the example template generator 502 includes a list ofuser-selectable conditions in the template. In some examples, theuser-selectable conditions are related to the event topic that has beenselected to trigger (at least in part) the workflow. In some suchexamples, the template generator 502 further causes the template toinclude an event schema associated with the event topic selected by thetenant administrator. The event schema identifies a set of fields. Forexample, if the event topic is a machine life cycle event topic, thenthe fields of the event schema will be related to the blueprints andmachines of the machine life cycle. In contrast, if the event topic isrelated to an approval event topic, the data fields of the event schemawill be related to approval policies. In some examples, the templatealso includes a text box into which the tenant administrator can enter apath (e.g., a link, an address to a folder in a file system, etc.) toconditions that are not included in the fields of the schema.

A block diagram illustrating an example exchange of information betweenthe example subscription manager 480, the example event broker 430 andthe example orchestrator 420 is shown in FIG. 5B. Although not shown inFIG. 5B, all communication to the example subscription manager 480 isreceived at the subscription manager communicator 510 for subsequenttransmission to the example subscription manager processor 512 andinformation transmitted out of the subscription manager 480 istransmitted via the example subscription manager communicator 510. Asdescribed above, each event topic has an associated event schema. Insome examples, when creating a workflow script to be executed inconnection with a subscription, the tenant administrator configures theworkflow script to include input parameters (or a single inputparameter) that use/consume all (or some) of the data contained in thedata fields of the event payload/schema. The name and type of such inputparameters are defined to match the name and type specified in the eventschema. In some such examples, the subscription manager processor 512(see FIG. 5A) of the subscription manager 480 extracts the event schemafrom the event message and supplies the extracted event schema as inputparameters to the orchestrator 420 for use in executing the customworkflow script. In addition, the custom workflow script can beconfigured to generate output parameters that match a desired schema.Thus, the generated output parameters that result from executing thecustom workflow script are supplied by the orchestrator 420 to thesubscription manager processor 512 of the subscription manager 480 afterthe custom workflow script is executed and the subscription managerprocessor 512 includes the output parameters in a reply messagetransmitted back to the event broker 430 for subsequent usage by otherworkflow subscriptions and/or for use by the service that produced theevent that triggered the workflow. It should be understood that inaddition to the input parameters, the subscription manager 480 suppliesa workflow identifier and any other information needed by theorchestrator to execute the custom workflow script.

In some examples, the tenant administrator can use the template toselect one (or more) of the fields in the event schema and to indicate adesired value against which a value stored in the field is to beevaluated. In some examples, as disclosed further below, when the valuestored in the selected field evaluates to (is equal to, greater than,less than, etc.) the desired value (e.g., True, False, a numericalvalue, etc.), the workflow is triggered. Thus, the field and the desiredvalue together form a condition to be met and/or satisfied before theselected workflow is triggered. In some examples, the user-selectableconditions (in addition to including the event schema fields) alsoincludes conditions that are more-generally related to the event topic(e.g., an event type, an event timestamp, a user name) and that are tobe evaluated to determine whether the workflow will be triggered. Thus,the tenant administrator uses the template generated by the templategenerator 502 to identify the features/characteristics of thesubscription (e.g., the workflow to be performed, an event topic uponwhich the operation of the workflow is to be predicated/based, and acondition and associated value to be met and/or satisfied before theworkflow will be triggered/executed).

In some examples, the subscription information entered using the exampletemplate generator 502 of the workflow subscription GUI 470 is suppliedto an example data collector 504. The data collector 504 assigns thesubscription information a subscription number or subscriptionidentifier and transmits the subscription information and thesubscription identifier to the workflow subscription GUI communicator506 for transmission to (and storage in) the example data storage 460(or in any other storage device). Initially, the subscriptionrepresented by the subscription information and the subscriptionidentifier is “inactive.” An inactive subscription is a subscriptionthat does not result in triggering of any workflows and/or monitoring ofany events.

In some examples, the template created by the template generator 502also includes a field by which the tenant administrator can elect tomake the subscription active. Activation of the subscription, (which canbe performed by changing a value stored in the field, selecting acheckbox, a drop down menu item, a radial button, etc.) causes the datacollector 504 to instruct the workflow subscription GUI communicator 506to mark the subscription information corresponding to the subscriptionidentifier that is stored in the example data storage 460 as “active.”In some examples, in response to activation of the subscription, thedata collector 504 also causes the workflow subscription GUIcommunicator 506 to send a notice to the example subscription manager480. The notice to the subscription manager 480 can include thesubscription identifier and information specifying that the subscriptionis active. In addition, the notice transmitted to the subscriptionmanager can include a storage address at which the subscriptioninformation is stored in the data storage 460. In some examples, thesubscription information and the subscription identifier are transmittedby the workflow subscription GUI communicator 506 to the subscriptionmanager 480 and the subscription manager 480 causes the subscriptioninformation and subscription identifier to be stored in the data storage460 and/or to be stored at the subscription manager 480 as described inthe following paragraph.

Referring still to FIG. 5A, the subscription identifier and thecorresponding subscription information (which can include a workflowidentifier identifying the workflow to be triggered in connection withthe subscription, the event topic of interest, the condition to beevaluated, the threshold value against which the condition is to beevaluated, an operator indicating the type of evaluation to beundertaken, and the status of the subscription (e.g., active/inactive))delivered to the example subscription manager 480 is received at anexample subscription manager communicator 510 of the subscriptionmanager 480. In some examples, the subscription communicator 510 causesthe subscription information to be stored in an example set of registers514 including a first register 514A, a second register 514B, a thirdregister 514C, a fourth register 514D, and a fifth register 514E. Insome examples, the first register 514A is used to store an activationflag/bit. If the activation flag/bit is set, the subscription is active.The second register 514B can be used to store the subscriptionidentifier. The third register 514C can be used to store the event topicof interest. The fourth register 514D can be used to store the conditionof interest and the fifth register 514E can be used to store thethreshold value against which the condition is to be evaluated. In someexamples, the threshold value stored in the fifth register 514E alsoincludes an operator indicating the type of evaluation to be performedby the example comparator 516. The operator may indicate that a valueassociated with the condition is to be equivalent to the thresholdvalue, to be greater than the threshold value, to be less than thethreshold value, or any combination thereof (e.g., greater than or equalto, less than or equal to, etc.) etc. If the flag/bit stored in thefirst register 514A indicates that the subscription is active, anexample subscription manager processor 512 causes the informationidentifying the event topic of interest (stored in the third register514C) to be transmitted to the example event broker 430 via thesubscription manager communicator 510. The event broker 430 responds byadding the event topic of interest to a list of event topics to monitorand further associates the event topic of interest with the subscriptionmanager 480. Thereafter, if an event (event message) corresponding tothe event topic of interest is received at the event broker 430, theevent broker 430 causes the event message to be transmitted to thesubscription manager 480. As described above, the events occur and/orare generated and/or performed by one or more the services 490. Uponoccurrence of the event, the one or more of the services 490 associatedwith the event notifies the event broker 430 which responds by notifyingthe subscription manager processor 512 via the subscription managercommunicator 510.

A block diagram illustrating an example exchange of information betweenthe example event broker 430 (see FIG. 4), the example subscriptionmanager processor 520, the example comparator 516, and the exampleorchestrator 420 (see FIG. 4) is shown in FIG. 5C. Although not shown inFIG. 5C, all communication to the example subscription manager 480 isreceived at the subscription manager communicator 510 for subsequenttransmission to the example subscription manager processor 512 andinformation transmitted out of the subscription manager 480 istransmitted via the example subscription manager communicator 510. Insome such examples, the event notification/message includes an eventpayload that identifies the event topic associated with the eventnotification (e.g. the event of interest) and includes event schemainformation. In some examples, upon receiving the event schemainformation, the subscription manager processor 512 causes the eventschema information to be transmitted to the example comparator 516. Thecomparator 516 uses the event schema information to identify the eventof interest and compares the event of interest to the event identifyinginformation stored in the example second register 514B. If there is amatch, thereby indicating that the event notification relates to theevent of interest for the subscription, the comparator 516 compares thecondition of interest stored in the example fourth register 514D to theevent schema. Upon identifying the condition interest in the eventschema, the comparator 516 compares a value corresponding to thecondition of interest in the event schema to the threshold value storedin the example fifth register 514E of the subscription using theoperator (also stored in the fifth register 514E). If the comparisonindicates the condition has been met (and/or satisfied), the comparator516 responds by obtaining the workflow identifier stored in the examplethird register 514C and causes the subscription manager processor 512 totransmit the workflow identifier to the orchestrator 420 via thesubscription manager communicator 510. (As described with reference toFIG. 5B), the subscription manager processor 512 may additionally causeany input parameters (extracted from, for example, the event schema) tobe supplied to the orchestrator 420 for use in executing the identifiedworkflow. The orchestrator 420 uses the workflow identifier (and, ifappropriate, input parameters) to execute the workflow 420. In someexamples, the workflow identifier indicates that a specialized workflowis to be executed. The specialized workflow can be a workflow containingtasks and/or steps embodied in and/or corresponding to an executablescript that the tenant administrator entered at the tenant administratorwork station 116 (see FIG. 1). When this occurs, the subscriptionmanager processor 512 can cause a storage address of the data storage460 at which the script is stored to be transmitted to the workfloworchestrator 420. In some such examples, the workflow orchestratorresponds by executing the tasks/steps contained at the storage addressof the data storage 460. In some examples, upon completion of theworkflow, the workflow orchestrator 420 can notify the subscriptionmanager processor 512 by way of the subscription manager communicator510. The subscription manager processor 512 can respond to thenotification by notifying the event broker 430. In some examples thenotification transmitted to the event broker 430 can include informationabout any aspect of the subscription and/or about execution of theworkflow.

In some examples, more than one condition can be included in thesubscription information. When more than one condition is included inthe subscription information, the trigger of the workflow can be basedon all, any, or none of the conditions being met and/or satisfied. Insome such examples, the template includes an option by which the tenantadministrator can select whether all, any, or none of the conditions areto be met and/or satisfied.

In some examples, the tenant administrator can use the templatedisplayed via the example tenant administrator work station 116 (seeFIG. 1) to make an active subscription inactive. In some such examples,the template includes a list of all subscriptions, both inactive andactive, and the tenant administrator unchecks a check box, selects aninactive selection from a drop down menu, deselects a radial button,etc., associated with the subscription to be deactivated. Inactivating aselected subscription via the template causes the data collector 504 totransmit a subscription identifier identifying the selected subscriptionto the subscription manager 480 by way of the workflow subscription GUIcommunicator 506. In addition to sending the subscription identifier, aninactivation notification is also transmitted. In response, thesubscription manager processor 512 causes the flag/bit stored in 514A ofthe selected subscription (e.g., subscription no. 1) to be unset.Because the flag/bit stored in 514A is no longer set, any future eventnotifications/messages received for the event associated withsubscription no. 1 will have no effect on triggering the workflowidentified in subscription no. 1.

By way of example, Table 1 illustrates an example provisioning eventtopic schema. In this example, the provisioning event topic schema isrelated to the provisioning of a virtual machine. In the illustratedexample, the machine is identified using an identifier, “id,” a machinename, a machine identifier on the hypervisor, a machine owner, and amachine type. As illustrated, the machine can be a physical machine or avirtual machine and includes a set of properties. The machine propertiescan include a blueprint name, a component identifier, a component typeidentifier, an endpoint identifier, a request identifier and a lifecyclestate that indicates a state, phase and event. In addition, the eventschema includes a virtual machine event field, a workflow next statefield, a virtual machine add or update properties field and a virtualmachine delete properties field.

TABLE 1 Example Provisioning Event Topic Schema {  machine : { id :STRING, /* IaaS machine ID */ name : STRING, /* machine name */externalReference : STRING, /* machine ID on the hypervisor */ owner :STRING, /* machine owner */ type : INTEGER, /* machine type: 0 - virtualmachine; 1 - physical machine; 2 - cloud machine */ properties :Properties /* machine properties, see notes below how to expose virtualmachine properties */  },  blueprintName : STRING, /* blueprint name */ componentId : STRING, /* component id */  componentTypeId : STRING, /*component, type id */  endpointId : STRING, /* endpoint id */  requestId: STRING, /* request id */  lifecycleState : { /* see Life Cycle StateDefinitions*/ state : STRING, phase : STRING, event : STRING  }, virtualMachineEvent : STRING, /* fire an event on that machine - onlyprocessed by Manager Service as consumer */  workflowNextState : STRING,/* force the workflow to a specific state - only processed by ManagerService as consumer */  virtualMachineAddOrUpdateProperties :Properties, /* properties on the machine to add/update - only processedby Manager Service as consumer */  virtualMachineDeleteProperties :Properties /* properties to remove from the machine - only processed byManager Service as consumer */ }

Based on the foregoing description, the example workflow subscriptionservice implemented by the example vA 320 provides features that permitworkflows to be triggered/executed based on a combination of events anduser-selected/user-specified conditions that are identified using theexample workflow subscription GUI 470. In previously available systems,a system administrator would be required to have an in-depthunderstanding of the workflow tasks and ordering of such tasks in orderto perform the same workflow-triggering operations that are availableusing the workflow subscription GUI 470. For example, the systemadministrator would be required to identify stubs in a workflow andmanually modify the existing workflow to enable the triggering ofadditional workflow tasks. Further, when the additional workflow taskswere no longer needed, the system administrator would be required to goback to the originally added tasks and remove all of the additional codeneeded to enable the additional tasks. The workflow subscription systemdisclosed herein enables the triggering of additional workflow/workflowtasks by making selections via a graphical user interface. Further, thetenant administrator can make the triggering of the workflow contingentupon any number of conditions.

While an example manner of implementing a workflow subscription servicein a cloud computing environment is illustrated in FIGS. 1-5, one ormore of the elements, processes and/or devices illustrated in FIGS. 1-5may be combined, divided, re-arranged, omitted, eliminated and/orimplemented in any other way. Further, the example application director106, example cloud provider 110, example cloud manager 138, exampledistributed execution managers 146A, 146B, example multi-machine service210, example load balancer 310, example virtual appliances 320-324,example component servers 330-336, example management endpoints 340-344,example management agents 350-356, example service provisioner 410,example orchestrator 420, example event broker 430, exampleauthentication provider 440, example internal reverse proxy 450, exampledata storage 460, example catalog 465, example workflow subscription GUI470, example subscription manager 480, example services 490, exampletemplate generator 502, example data collector 504, example workflowsubscription GUI communicator 506, example subscription managercommunicator 510, example subscription manager processor 512, exampleregisters 514A-514E, example comparator 516, and/or, more generally, theexample systems 100 and/or 300 of FIGS. 1-5 can be implemented byhardware, software, firmware and/or any combination of hardware,software and/or firmware. Thus, for example, any of the exampleapplication director 106, example cloud provider 110, example cloudmanager 138, example distributed execution managers 146A, 146B, examplemulti-machine service 210, example load balancer 310, example virtualappliances 320-324, example component servers 330-336, examplemanagement endpoints 340-344, example management agents 350-356, exampleservice provisioner 410, example orchestrator 420, example event broker430, example authentication provider 440, example internal reverse proxy450, example data storage 460, example catalog 465, example workflowsubscription GUI 470, example subscription manager 480, example services490, example template generator 502, example data collector 504, exampleworkflow subscription GUI communicator 506, example subscription managercommunicator 510, example subscription manager processor 512, exampleregisters 514A-514E, example comparator 516, and/or, more generally, theexample systems 100 and/or 300 of FIGS. 1-5 can be implemented by one ormore analog or digital circuit(s), logic circuits, programmableprocessor(s), application specific integrated circuit(s) (ASIC(s)),programmable logic device(s) (PLD(s)) and/or field programmable logicdevice(s) (FPLD(s)). When reading any of the apparatus or system claimsof this patent to cover a purely software and/or firmwareimplementation, at least one of the example application director 106,example cloud provider 110, example cloud manager 138, exampledistributed execution managers 146A, 146B, example multi-machine service210, example load balancer 310, example virtual appliances 320-324,example component servers 330-336, example management endpoints 340-344,example management agents 350-356, example service provisioner 410,example orchestrator 420, example event broker 430, exampleauthentication provider 440, example internal reverse proxy 450, exampledata storage 460, example catalog 465, example workflow subscription GUI470, example subscription manager 480, example services 490, exampletemplate generator 502, example data collector 504, example workflowsubscription GUI communicator 506, example subscription managercommunicator 510, example subscription manager processor 512, exampleregisters 514A-514E, example comparator 516, and/or, more generally, theexample systems 100 and/or 300 of FIGS. 1-5 is/are hereby expresslydefined to include a tangible computer readable storage device orstorage disk such as a memory, a digital versatile disk (DVD), a compactdisk (CD), a Blu-ray disk, etc. storing the software and/or firmware.Further still, the example application director 106, example cloudprovider 110, example cloud manager 138, example distributed executionmanagers 146A, 146B, example multi-machine service 210, example loadbalancer 310, example virtual appliances 320-324, example componentservers 330-336, example management endpoints 340-344, examplemanagement agents 350-356, example service provisioner 410, exampleorchestrator 420, example event broker 430, example authenticationprovider 440, example internal reverse proxy 450, example data storage460, example catalog 465, example workflow subscription GUI 470, examplesubscription manager 480, example services 490, example templategenerator 502, example data collector 504, example workflow subscriptionGUI communicator 506, example subscription manager communicator 510,example subscription manager processor 512, example registers 514A-514E,example comparator 516, and/or, more generally, the example systems 100and/or 300 of FIGS. 1-5 may include one or more elements, processesand/or devices in addition to, or instead of, those illustrated in FIGS.1-5, and/or may include more than one of any or all of the illustratedelements, processes and devices.

Flowcharts representative of example machine readable instructions thatmay be executed to implement the example virtual appliances 320, exampleservice provisioner 410, example orchestrator 420, example event broker430, example authentication provider 440, example internal reverse proxy450, example data storage 460, example catalog 465, example workflowsubscription GUI 470, example subscription manager 480, example services490, example template generator 502, example data collector 504, exampleworkflow subscription GUI communicator 506, example subscription managercommunicator 510, example subscription manager processor 512, exampleregisters 514A-514E, example comparator 516, and/or to deploy and managethe example application director 106, example cloud provider 110,example cloud manager 138, example distributed execution managers 146A,146B, example multi-machine service 210, example load balancer 310,example virtual appliances 320-324, example component servers 330-336,example management endpoints 340-344, example management agents 350-356,and/or, more generally, the example systems 100 and/or 300 of FIGS. 1-5are shown in FIGS. 6-8. In these examples, the machine readableinstructions implement programs for execution by a processor such as theprocessor 1012 shown in the example processor platform 1000 discussedbelow in connection with FIG. 10. The programs may be embodied insoftware stored on a tangible computer readable storage medium such as aCD-ROM, a floppy disk, a hard drive, a digital versatile disk (DVD), aBlu-ray disk, or a memory associated with the processor 1012, but theentire program and/or parts thereof could alternatively be executed by adevice other than the processor 1012 and/or embodied in firmware ordedicated hardware. Further, although the example programs are describedwith reference to the flowcharts illustrated in FIGS. 6-8, many othermethods of deploying, evaluating, and installing services on componentservers in accordance with the teachings of this disclosure mayalternatively be used. For example, the order of execution of the blocksmay be changed, and/or some of the blocks described may be changed,eliminated, or combined.

As mentioned above, the example processes of FIGS. 6-8 may beimplemented using coded instructions (e.g., computer and/or machinereadable instructions) stored on a tangible computer readable storagemedium such as a hard disk drive, a flash memory, a read-only memory(ROM), a compact disk (CD), a digital versatile disk (DVD), a cache, arandom-access memory (RAM) and/or any other storage device or storagedisk in which information is stored for any duration (e.g., for extendedtime periods, permanently, for brief instances, for temporarilybuffering, and/or for caching of the information). As used herein, theterm tangible computer readable storage medium is expressly defined toinclude any type of computer readable storage device and/or storage diskand to exclude propagating signals and to exclude transmission media. Asused herein, “tangible computer readable storage medium” and “tangiblemachine readable storage medium” are used interchangeably. In someexamples, the example processes of FIGS. 6-8 may be implemented usingcoded instructions (e.g., computer and/or machine readable instructions)stored on a non-transitory computer and/or machine readable medium suchas a hard disk drive, a flash memory, a read-only memory, a compactdisk, a digital versatile disk, a cache, a random-access memory and/orany other storage device or storage disk in which information is storedfor any duration (e.g., for extended time periods, permanently, forbrief instances, for temporarily buffering, and/or for caching of theinformation). As used herein, the term non-transitory computer readablemedium is expressly defined to include any type of computer readablestorage device and/or storage disk and to exclude propagating signalsand to exclude transmission media. As used herein, when the phrase “atleast” is used as the transition term in a preamble of a claim, it isopen-ended in the same manner as the term “comprising” is open ended.Comprising and all other variants of “comprise” are expressly defined tobe open-ended terms. Including and all other variants of “include” arealso defined to be open-ended terms. In contrast, the term consistingand/or other forms of consist are defined to be close-ended terms.

FIG. 6 depicts a flowchart representative of computer readableinstructions that may be executed to implement the workflow subscriptionservice using the example workflow subscription GUI 470 and the examplesubscription manager 480 of the example vA 320 of FIG. 4. An exampleprogram 600 is illustrated in FIG. 6. Initially, at block 610, theworkflow subscription GUI 470 generates a display having event topics.At block 620, the workflow subscription GUI 470 responds touser-selection of an event topic by causing a corresponding event schemato be displayed. As described above, the event schema includes a set offields. At block 630, the workflow subscription GUI 470 responds touser-selection of one of the fields of the event schema by collecting(from user-input) a threshold value. As further described above, thethreshold value is a value that will be compared against a valueassociated with the selected field of the event schema. At block 640,the workflow subscription GUI 470 responds to the entry of the thresholdvalue by supplying an event topic identifier identifying the selectedevent topic, a field identifier identifying the selected field and thethreshold value to the subscription manager 480. In some examples, theworkflow subscription GUI 470 causes the information to be stored in theexample data storage 460 and then identifies a storage address of theinformation to the subscription manager 480. In some examples, theworkflow subscription GUI 470 supplies the information directly to thesubscription manager 480. In some examples, the workflow subscriptionGUI 470 causes the information to be stored in the data storage 460 andalso supplies the information to the subscription manager 480. At block650, the subscription manager causes the triggering of a user specifiedworkflow to be conditioned upon the detection of an event notificationcorresponding to the user-selected event, and a value associated withthe user-selected field of the event schema having a specifiedrelationship (e.g., equal to, greater than, less than, etc.) to thethreshold value. In some examples, the specified relationship isspecified by the user via the display generated by the workflowsubscription GUI 470. Thereafter, the program 600 ends.

FIG. 7 depicts a flowchart representative of computer readableinstructions that may be executed to implement the workflow subscriptionservice using the example subscription manager 480 of the example vA 320of FIG. 4. An example program 700 is illustrated in FIG. 7. Initially,at block 710, the example subscription manager processor 512 of thesubscription manager 480 transmits information via the examplesubscription manager communicator 510 to the example event broker 430.The transmitted information includes a subscription to a user selectedevent topic. At block 720, the subscription manager processor 512responds to an event notification received from the event broker. Inresponse to the event notification, the subscription manager processor512 reviews the payload included in the received event notification toidentify the event topic to which the event notification corresponds.Provided that at least one subscription managed by the subscriptionmanager 480 is subscribed to the identified event topic, thesubscription manager processor 512 identifies a field of interestincluded in the event payload. As further described above, the field ofinterest to be identified in the event payload can be stored in any of aset of registers 514A, 514B, 514C, 514D, 514E. At block 730, thesubscription manager processor 512 identifies a value contained in thepayload information in the field of interest. At block 740, thesubscription manager processor 512 causes the example comparator 516 ofthe example subscription manager 480 to compare the value contained inthe payload information in the field of interest with a threshold valuestored in one of the registers 514A, 514B. 514C, 514D, 514E. At a block750, provided that the value contained in the payload information in thefield of interest bears a specific relationship (e.g., equal to, lessthan, greater than, etc.) to the threshold value, the subscriptionmanager processor 512 causes a workflow to be triggered. Thereafter, theprogram 700 ends.

FIG. 8 is a block diagram of an example processor platform 800structured to execute the instructions of FIGS. 6 and 7 to implement theexample systems, operation, and management of FIGS. 1-5. The processorplatform 800 of the illustrated example includes a processor 812. Theprocessor 812 of the illustrated example is hardware. For example, theprocessor 812 can be implemented by one or more integrated circuits,logic circuits, microprocessors or controllers from any desired familyor manufacturer.

The processor 812 of the illustrated example includes a local memory 813(e.g., a cache), and executes instructions to implement the examplesystems 100, 300 or portions thereof, such as the vA 320-324, componentserver 330-336, management endpoint 340-344, and management agent350-356. The processor 812 of the illustrated example is incommunication with a main memory including a volatile memory 814 and anon-volatile memory 816 via a bus 818. The volatile memory 814 may beimplemented by Synchronous Dynamic Random Access Memory (SDRAM), DynamicRandom Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM)and/or any other type of random access memory device. The non-volatilememory 816 may be implemented by flash memory and/or any other desiredtype of memory device. Access to the main memory 814, 816 is controlledby a memory controller.

The processor platform 800 of the illustrated example also includes aninterface circuit 820. The interface circuit 820 may be implemented byany type of interface standard, such as an Ethernet interface, auniversal serial bus (USB), and/or a PCI express interface.

In the illustrated example, one or more input devices 822 are connectedto the interface circuit 820. The input device(s) 822 permit(s) a userto enter data and commands into the processor 812. The input device(s)can be implemented by, for example, an audio sensor, a microphone, akeyboard, a button, a mouse, a touchscreen, a track-pad, a trackball,isopoint and/or a voice recognition system. In some examples, the inputdevice(s) 822 are used to implement the tenant administrator workstation 116 (see FIG. 1).

One or more output devices 824 are also connected to the interfacecircuit 820 of the illustrated example. The output devices 824 can beimplemented, for example, by display devices (e.g., a light emittingdiode (LED), an organic light emitting diode (OLED), a liquid crystaldisplay, a cathode ray tube display (CRT), a touchscreen, a tactileoutput device, a printer and/or speakers). The interface circuit 820 ofthe illustrated example, thus, typically includes a graphics drivercard, a graphics driver chip or a graphics driver processor. In someexamples the output device(s) 824 are used to implement the tenantadministrator work station 116 (see FIG. 1).

The interface circuit 820 of the illustrated example also includes acommunication device such as a transmitter, a receiver, a transceiver, amodem and/or network interface card to facilitate exchange of data withexternal machines (e.g., computing devices of any kind) via a network826 (e.g., an Ethernet connection, a digital subscriber line (DSL), atelephone line, coaxial cable, a cellular telephone system, etc.).

The processor platform 800 of the illustrated example also includes oneor more mass storage devices 828 for storing software and/or data.Examples of such mass storage devices 828 include flash devices, floppydisk drives, hard drive disks, optical compact disk (CD) drives, opticalBlu-ray disk drives, RAID systems, and optical digital versatile disk(DVD) drives.

Coded instructions 832 representative of the example machine readableinstructions of FIGS. 6 and 7 may be stored in the mass storage device828, in the volatile memory 814, in the non-volatile memory 816, and/oron a removable tangible computer readable storage medium such as a CD orDVD.

In the example of FIG. 8, the processor 812 implements the virtualappliance 320 (and vAs 322-324) and the component server 330 (andservers 332-336) and their components including the service provisioner410, orchestrator 420, event broker 430, authentication provider 440,proxy 450, data storage 460, subscription manager 480, the workflowsubscription GUI 470, the services 490, catalog 465, etc. In certainexamples, as discussed herein, the hardware of processor 812 isvirtualized using virtualization such as VMs and/or containers. In theexample of FIG. 8, the virtual appliance 320 can be implemented by oneor more VMs or containers, so as to virtualize the hardware of processor812.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

What is claimed is:
 1. An apparatus comprising: memory; and at least oneprocessor to execute computer readable instructions to implement avirtual appliance in a cloud computing environment, the virtualappliance comprising: a graphical user interface to present a templateon a display device, the template corresponding to an event topic, theevent topic to trigger a workflow associated with a first workflowsubscription, the first workflow subscription included in a plurality ofworkflow subscriptions having a hierarchy, the template to include afirst field to specify whether at least one other workflow subscriptionassociated with the event topic is to be blocked until a hierarchicallydominant workflow subscription has at least one of been notified of theevent topic or taken action based on the event topic; and a subscriptionmanager to trigger the workflow in response to an event notificationassociated with the event topic.
 2. The apparatus of claim 1, whereinthe first workflow subscription is the hierarchically dominant workflowsubscription.
 3. The apparatus of claim 1, wherein the event topic isassociated with a service, and the template further includes a secondfield to specify whether a reply notification is to be sent to theservice in response to completion of the completion of the workflowafter the workflow has been triggered based on the event notification.4. The apparatus of claim 1, wherein the subscription manager is totrigger the workflow in response to the event notification associatedwith the event topic and satisfaction of a condition associated with theevent topic.
 5. The apparatus of claim 4, wherein the event notificationincludes a payload, the payload includes a value associated with thecondition, and the subscription manager is to compare the value with athreshold to determine whether the condition is satisfied.
 6. Theapparatus of claim 5, wherein the subscription manager includes: a firstregister to store an activation flag to indicate whether the firstworkflow subscription is active, the activation flag configurable viathe graphical user interface; a second register to store the valueassociated with the condition; and a third register to store thethreshold and an operator to specify a type of comparison to beperformed with the threshold and the value associated with thecondition, the threshold and the operator configurable via the graphicaluser interface.
 7. A non-transitory computer readable storage mediumcomprising computer readable instructions that, when executed, cause atleast one processor to at least: initiate display of a templatecorresponding to an event topic, the event topic to trigger a workflowassociated with a first workflow subscription, the first workflowsubscription included in a plurality of workflow subscriptions having ahierarchy, the template to include a first field to specify whether atleast one other workflow subscription associated with the event topic isto be blocked until a hierarchically dominant workflow subscription hasat least one of been notified of the event topic or taken action basedon the event topic; and trigger the workflow in response to an eventnotification associated with the event topic.
 8. The non-transitorycomputer readable storage medium of claim 7, wherein the first workflowsubscription is the hierarchically dominant workflow subscription. 9.The non-transitory computer readable storage medium of claim 7, whereinthe event topic is associated with a service, and the template furtherincludes a second field to specify whether a reply notification is to besent to the service in response to completion of the completion of theworkflow after the workflow has been triggered based on the eventnotification.
 10. The non-transitory computer readable storage medium ofclaim 7, wherein the instructions, when executed, cause the at least oneprocessor to trigger the workflow in response to the event notificationassociated with the event topic and satisfaction of a conditionassociated with the event topic.
 11. The non-transitory computerreadable storage medium of claim 10, wherein the event notificationincludes a payload, the payload includes a value associated with thecondition, and the instructions, when executed, cause the at least oneprocessor to compare the value with a threshold to determine whether thecondition is satisfied.
 12. The non-transitory computer readable storagemedium of claim 11, wherein the instructions, when executed, cause theat least one processor to: store an activation flag in a first register,the activation flag to indicate whether the first workflow subscriptionis active, the activation flag configurable via a graphical userinterface; store the value associated with the condition in a secondregister; and store the threshold and an operator in a third register,the operator to specify a type of comparison to be performed with thethreshold and the value associated with the condition, the threshold andthe operator configurable via the graphical user interface.
 13. Thenon-transitory computer readable storage medium of claim 7, wherein theinstructions, when executed, cause the at least one processor tosubscribe to an event broker to receive the event notificationassociated with the event topic.
 14. A method for a virtual appliance ina cloud computing environment, the method comprising: causing, byexecuting an instruction with at least one processor, display of atemplate corresponding to an event topic, the event topic to trigger aworkflow associated with a first workflow subscription, the firstworkflow subscription included in a plurality of workflow subscriptionshaving a hierarchy, the template to include a first field to specifywhether at least one other workflow subscription associated with theevent topic is to be blocked until a hierarchically dominant workflowsubscription has at least one of been notified of the event topic ortaken action based on the event topic; and triggering, by executing aninstruction with the at least one processor, the workflow in response toan event notification associated with the event topic.
 15. The method ofclaim 14, wherein the first workflow subscription is the hierarchicallydominant workflow subscription.
 16. The method of claim 14, wherein theevent topic is associated with a service, and the template furtherincludes a second field to specify whether a reply notification is to besent to the service in response to completion of the completion of theworkflow after the workflow has been triggered based on the eventnotification.
 17. The method of claim 14, wherein the triggeringincludes triggering the workflow in response to the event notificationassociated with the event topic and satisfaction of a conditionassociated with the event topic.
 18. The method of claim 17, wherein theevent notification includes a payload, the payload includes a valueassociated with the condition, and further including comparing the valuewith a threshold to determine whether the condition is satisfied. 19.The method of claim 18, further including: storing an activation flag ina first register, the activation flag to indicate whether the firstworkflow subscription is active, the activation flag configurable via agraphical user interface; storing the value associated with thecondition in a second register; and storing the threshold and anoperator in a third register, the operator to specify a type ofcomparison to be performed with the threshold and the value associatedwith the condition, the threshold and the operator configurable via thegraphical user interface.
 20. The method of claim 14, further includingsubscribing to an event broker to receive the event notificationassociated with the event topic.